Effect of La3+ and Nd3+ on the microwave dielectric properties of (Pb0.5Ca0.5)(Fe0.5Nb0.5)O3 ceramics

Microwave dielectric properties of A-site substitution by both La3+ and Nd3+ in (Pb0.5Ca0.5)(Fe0.5Nb0.5)O-3 system were investigated. Microwave dielectric properties of A-site charge unbalance substitution of [(Pb0.5Ca0.5)(1 -) (x) (La0.5Nd0.5)(x)](Fe0.5Nb0.5)O3 + delta (PCLNFN) were improved because the solid solution of small amount of surplus (La, Nd)(3+) with (Pb, Ca)(2+) could eliminate oxygen vacancies; the formation of secondary phase (pyrochlore phase) was also caused by surplus (La, Nd)(3+). The decreasing of dielectric constant with the increase of (La, Nd)(3+) content was due to the formation of pyrochlore phase. Qf values were almost unchanged at x = 0.02-0.08, but the temperature coefficient of resonant frequency (TCF) was decreased. Typically, at x = 0.06, the excellent microwave dielectric properties of Qf = 5822 GHz, epsilon(r) = 99.9 with TCF = 0 ppm/degreesC were obtained. (C) 2002 Elsevier Science B.V. All rights reserved.